secondlife/viewer#2638: Don't clear big render target if all pixels will be replaced

4 files changed, 37 insertions, 17 deletions

diff --git a/indra/llrender/llrendertarget.cpp b/indra/llrender/llrendertarget.cpp
index 38bc5ff331..c72f8fa2ba 100644
--- a/indra/llrender/llrendertarget.cpp
+++ b/indra/llrender/llrendertarget.cpp
@@ -51,6 +51,7 @@ void check_framebuffer_status()
 }
 
 bool LLRenderTarget::sUseFBO = false;
+bool LLRenderTarget::sClearOnInvalidate = false;
 U32 LLRenderTarget::sCurFBO = 0;
 
 
@@ -473,6 +474,13 @@ void LLRenderTarget::clear(U32 mask_in)
     }
 }
 
+void LLRenderTarget::invalidate(U32 mask_in)
+{
+    LL_PROFILE_ZONE_SCOPED_CATEGORY_DISPLAY;
+    if (!sClearOnInvalidate) { return; }
+    clear(mask_in);
+}
+
 U32 LLRenderTarget::getTexture(U32 attachment) const
 {
     if (attachment >= mTex.size())
@@ -584,7 +592,6 @@ void LLRenderTarget::swapFBORefs(LLRenderTarget& other)
     llassert(!other.isBoundInStack());
 
     // Must be same type
-    llassert(sUseFBO == other.sUseFBO);
     llassert(mResX == other.mResX);
     llassert(mResY == other.mResY);
     llassert(mInternalFormat == other.mInternalFormat);
diff --git a/indra/llrender/llrendertarget.h b/indra/llrender/llrendertarget.h
index cd3290cf66..f066534cf4 100644
--- a/indra/llrender/llrendertarget.h
+++ b/indra/llrender/llrendertarget.h
@@ -63,6 +63,7 @@ class LLRenderTarget
 public:
     // Whether or not to use FBO implementation
     static bool sUseFBO;
+    static bool sClearOnInvalidate;
     static U32 sBytesAllocated;
     static U32 sCurFBO;
     static U32 sCurResX;
@@ -128,11 +129,17 @@ public:
     //  Asserts that this target is not currently bound in the stack
     void bindTarget();
 
-    //clear render targer, clears depth buffer if present,
+    //clear render target, clears depth buffer if present,
     //uses scissor rect if in copy-to-texture mode
     // asserts that this target is currently bound
     void clear(U32 mask = 0xFFFFFFFF);
 
+    //same as clear, except may be a no-op depending on configuration
+    //useful to indicate the buffer is about to be overwritten and we
+    //don't care about its previous contents
+    //depending on the GPU, one may be more expensive than the other
+    void invalidate(U32 mask = 0xFFFFFFFF);
+
     //get applied viewport
     void getViewport(S32* viewport);
 
diff --git a/indra/newview/app_settings/settings.xml b/indra/newview/app_settings/settings.xml
index 82eb98b06b..2cbb493b91 100644
--- a/indra/newview/app_settings/settings.xml
+++ b/indra/newview/app_settings/settings.xml
@@ -7330,6 +7330,17 @@
     <key>Value</key>
     <integer>-1</integer>
   </map>
+  <key>RenderBufferClearOnInvalidate</key>
+  <map>
+    <key>Comment</key>
+    <string>Whether to call glClear on render buffers that will be fully overwritten with new contents</string>
+    <key>Persist</key>
+    <integer>1</integer>
+    <key>Type</key>
+    <string>Boolean</string>
+    <key>Value</key>
+    <integer>0</integer>
+  </map>
   <key>RenderCompressTextures</key>
   <map>
     <key>Comment</key>
diff --git a/indra/newview/pipeline.cpp b/indra/newview/pipeline.cpp
index fe02742aac..19868d2eef 100644
--- a/indra/newview/pipeline.cpp
+++ b/indra/newview/pipeline.cpp
@@ -576,6 +576,7 @@ void LLPipeline::init()
     connectRefreshCachedSettingsSafe("RenderScreenSpaceReflectionAdaptiveStepMultiplier");
     connectRefreshCachedSettingsSafe("RenderScreenSpaceReflectionGlossySamples");
     connectRefreshCachedSettingsSafe("RenderBufferVisualization");
+    connectRefreshCachedSettingsSafe("RenderBufferClearOnInvalidate");
     connectRefreshCachedSettingsSafe("RenderMirrors");
     connectRefreshCachedSettingsSafe("RenderHeroProbeUpdateRate");
     connectRefreshCachedSettingsSafe("RenderHeroProbeConservativeUpdateMultiplier");
@@ -1084,6 +1085,7 @@ void LLPipeline::refreshCachedSettings()
     RenderScreenSpaceReflectionAdaptiveStepMultiplier = gSavedSettings.getF32("RenderScreenSpaceReflectionAdaptiveStepMultiplier");
     RenderScreenSpaceReflectionGlossySamples = gSavedSettings.getS32("RenderScreenSpaceReflectionGlossySamples");
     RenderBufferVisualization = gSavedSettings.getS32("RenderBufferVisualization");
+    LLRenderTarget::sClearOnInvalidate = gSavedSettings.getBOOL("RenderBufferClearOnInvalidate");
     RenderMirrors = gSavedSettings.getBOOL("RenderMirrors");
     RenderHeroProbeUpdateRate = gSavedSettings.getS32("RenderHeroProbeUpdateRate");
     RenderHeroProbeConservativeUpdateMultiplier = gSavedSettings.getS32("RenderHeroProbeConservativeUpdateMultiplier");
@@ -7147,7 +7149,7 @@ void LLPipeline::copyScreenSpaceReflections(LLRenderTarget* src, LLRenderTarget*
         LLRenderTarget& depth_src = mRT->deferredScreen;
 
         dst->bindTarget();
-        dst->clear();
+        dst->invalidate();
         gCopyDepthProgram.bind();
 
         S32 diff_map = gCopyDepthProgram.getTextureChannel(LLShaderMgr::DIFFUSE_MAP);
@@ -7334,7 +7336,7 @@ void LLPipeline::applyFXAA(LLRenderTarget* src, LLRenderTarget* dst)
 
             // bake out texture2D with RGBL for FXAA shader
             mFXAAMap.bindTarget();
-            mFXAAMap.clear(GL_COLOR_BUFFER_BIT);
+            mFXAAMap.invalidate(GL_COLOR_BUFFER_BIT);
 
             shader = &gGlowCombineFXAAProgram;
             shader->bind();
@@ -7433,7 +7435,7 @@ void LLPipeline::generateSMAABuffers(LLRenderTarget* src)
             LLGLSLShader& edge_shader = gSMAAEdgeDetectProgram[fsaa_quality];
 
             dest.bindTarget();
-            dest.clear(GL_COLOR_BUFFER_BIT);
+            dest.invalidate(GL_COLOR_BUFFER_BIT);
 
             edge_shader.bind();
             edge_shader.uniform4fv(sSmaaRTMetrics, 1, rt_metrics);
@@ -7476,7 +7478,7 @@ void LLPipeline::generateSMAABuffers(LLRenderTarget* src)
             LLGLSLShader& blend_weights_shader = gSMAABlendWeightsProgram[fsaa_quality];
 
             dest.bindTarget();
-            dest.clear(GL_COLOR_BUFFER_BIT);
+            dest.invalidate(GL_COLOR_BUFFER_BIT);
 
             blend_weights_shader.bind();
             blend_weights_shader.uniform4fv(sSmaaRTMetrics, 1, rt_metrics);
@@ -7552,7 +7554,7 @@ void LLPipeline::applySMAA(LLRenderTarget* src, LLRenderTarget* dst)
             LLGLSLShader& blend_shader = gSMAANeighborhoodBlendProgram[fsaa_quality];
 
             bound_target->bindTarget();
-            bound_target->clear(GL_COLOR_BUFFER_BIT);
+            bound_target->invalidate(GL_COLOR_BUFFER_BIT);
 
             blend_shader.bind();
             blend_shader.uniform4fv(sSmaaRTMetrics, 1, rt_metrics);
@@ -8330,9 +8332,7 @@ void LLPipeline::renderDeferredLighting()
                 LLGLSLShader& sun_shader = gCubeSnapshot ? gDeferredSunProbeProgram : gDeferredSunProgram;
                 bindDeferredShader(sun_shader, deferred_light_target);
                 mScreenTriangleVB->setBuffer();
-                glClearColor(1, 1, 1, 1);
-                deferred_light_target->clear(GL_COLOR_BUFFER_BIT);
-                glClearColor(0, 0, 0, 0);
+                deferred_light_target->invalidate(GL_COLOR_BUFFER_BIT);
 
                 sun_shader.uniform2f(LLShaderMgr::DEFERRED_SCREEN_RES,
                                               (GLfloat)deferred_light_target->getWidth(),
@@ -8356,9 +8356,7 @@ void LLPipeline::renderDeferredLighting()
             LL_PROFILE_GPU_ZONE("soften shadow");
             // blur lightmap
             screen_target->bindTarget();
-            glClearColor(1, 1, 1, 1);
-            screen_target->clear(GL_COLOR_BUFFER_BIT);
-            glClearColor(0, 0, 0, 0);
+            screen_target->invalidate(GL_COLOR_BUFFER_BIT);
 
             bindDeferredShader(gDeferredBlurLightProgram);
 
@@ -8410,11 +8408,8 @@ void LLPipeline::renderDeferredLighting()
             deferred_light_target->flush();
             unbindDeferredShader(gDeferredBlurLightProgram);
         }
-
         screen_target->bindTarget();
-        // clear color buffer here - zeroing alpha (glow) is important or it will accumulate against sky
-        glClearColor(0, 0, 0, 0);
-        screen_target->clear(GL_COLOR_BUFFER_BIT);
+        screen_target->invalidate(GL_COLOR_BUFFER_BIT);
 
         if (RenderDeferredAtmospheric)
         {  // apply sunlight contribution